Caseous Lynphadenitis in Sheep

Summary written by Michael Fontaine BSc PhD

Taken from Moredun Foundation Newsheet Volume 5 No. 1 (2009)

Caseous lymphadenitis (CLA) is a chronic bacterial disease of sheep and goats characterised by abscess development in the lymph nodes and other tissues.

CLA can result in chronic wasting, resulting in significant welfare and financial implications.

CLA lesions can necessitate carcase trimming at abattoir, and in severe cases may lead to carcase condemnation.

Currently (February 2009), the disease is well-established within Great Britain and Northern Ireland.

C. pseudotuberculosis, the causative organism of CLA, can survive in the environment for several months and is highly infectious.

Antibiotic treatment is ineffective.

Although CLA was once mainly seen in the terminal sire breeds, the disease has now become established within the national flock.

Direct contact with pus from CLA lesions is the main source of new infections, however, infectious aerosol from animals with lung lesions has also been shown to be a means of disease spread.

Sheep or goats displaying chronic abscesses should be isolated and subjected to immediate veterinary and bacteriological investigation

Control measures should include quarantining (of both animals and premises), screening of imported animals, the cull of infected animals and rigorous hygiene procedures. Shearing equipment should be dipped in strong disinfectant or chlorine bleach before and after use.

Older animals should be handled last during routine procedures.

A heightened awareness of this disease and prompt veterinary investigation of suspect cases is essential. At present, CLA is not a notifiable disease.

A CLA diagnostic blood-test has been developed by Moredun and SAC scientists and a testing service is provided by SAC.

The full news sheet for any of the disease summaries can be ordered from the Moredun Foundation by using the following request form. The first news sheet title requested is free*, further news sheet titles are charged at £5.00 per copy (including postage).

*offer limited to one news sheet title per postal address in any one year. After that each news sheet will be charged at the standard price of £5.00 (including postage).

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